Abstract:
Data from the Ultraviolet Spectrometer and Polarimeter (UVSP) consist of photon counts at selected UV wavelengths in the 1170 - 3500 A band from detectors which are used in a variety of modes to build up solar images with various spatial dimensions. Spectral resolution in some observations is as good as 0.01 A.

Each observing sequence is termed an experiment, and given an experiment number. A ... complete data base exists, in which all of the experiments appear, and which may be searched according to fields that identify experiment types. This data base is available on-line at the Solar Data Analysis Center (SDAC). There are also various special data sets (e.g. ozone experiments) at the SDAC.

Reformatted data from 1980 to the present are archived on optical disk. Requests for data should be addressed to the SDAC.

The UVSP was designed to measure the relatively low-temperature plasmas (5000 to 200,000 K) in flares, active regions and the quiet Sun. The wavelength range given above could be scanned. Spatial resolution in some observations is as good as 1 arc sec, and the field of view could be varied by raster scanning to build up images as large as 256 arc sec square. (Some larger images were made by adjusting the spacecraft fine pointing between rasters.) Dopplergrams were possible using two detectors, one on either side of a spectral line. Time resolution could be as fast as 64 ms. Linear and circular polarimetry were possible. Any combination of timing, slit size, spatial step size, polarimetry and wavelength scanning in any order was possible.

Many of the various instrument modes have been utilised during its operational life, so there is a great variety of kinds of data arrays (with differing dimensionality in spatial, spectral and temporal dimensions). There are fixed-wavelength image sequences of every size from 3 x 3 pixels to full-scale 256 x 256 arc-sec-square rasters, and any of these sequences may have been interspersed with similar ones at other wavelengths. One common observing strategy was to obtain small-scale images of the brightest area early in a flare, to maximize time resolution during the impulsive phase, and to make larger-scale rasters later in the flare when the gradual phase typically occurred.

Observations of stratospheric ozone have also been made, exploiting the passage of sunlight through the Earth's atmosphere as SMM enters or emerges from the Earth's shadow during its 90-minute orbit. These observations have provided unique measurements of ozone concentration in mid-latitudes.